A chemical reaction is a process that leads to the chemical transformation of one set of chemical substances to another. Classically, chemical reactions encompass changes that only involve the positions of electrons in the forming and breaking of chemical bonds between atoms, with no change to the nuclei (no change to the elements present), and can often be described by a chemical equation. Nuclear chemistry is a sub-discipline of chemistry that involves the chemical reactions of unstable and radioactive elements where both electronic and nuclear changes can occur.
The substance (or substances) initially involved in a chemical reaction are called reactants or reagents. Chemical reactions are usually characterized by a chemical change, and they yield one or more products, which usually have properties different from the reactants. Reactions often consist of a sequence of individual sub-steps, the so-called elementary reactions, and the information on the precise course of action is part of the reaction mechanism. Chemical reactions are described with chemical equations, which symbolically present the starting materials, end products, and sometimes intermediate products and reaction conditions.
Chemical reactions happen at a characteristic reaction rate at a given temperature and chemical concentration. Typically, reaction rates increase with increasing temperature because there is more thermal energy available to reach the activation energy necessary for breaking bonds between atoms.
Reactions may proceed in the forward or reverse direction until they go to completion or reach equilibrium. Reactions that proceed in the forward direction to approach equilibrium are often described as spontaneous, requiring no input of free energy to go forward. Non-spontaneous reactions require input of free energy to go forward (examples include charging a battery by applying an external electrical power source, or photosynthesis driven by absorption of electromagnetic radiation in the form of sunlight).
A reaction may be classified as redox in which oxidation and reduction occur or nonredox in which there is no oxidation and reduction occurring. Most simple redox reactions may be classified as combination, decomposition, or single displacement reactions.
Different chemical reactions are used during chemical synthesis in order to obtain a desired product. In biochemistry, a consecutive series of chemical reactions (where the product of one reaction is the reactant of the next reaction) form metabolic pathways. These reactions are often catalyzed by protein enzymes. Enzymes increase the rates of biochemical reactions, so that metabolic syntheses and decompositions impossible under ordinary conditions can occur at the temperatures and concentrations present within a cell.
The general concept of a chemical reaction has been extended to reactions between entities smaller than atoms, including nuclear reactions, radioactive decays, and reactions between elementary particles, as described by quantum field theory.
Homework Statement
Give all possible products of the following reaction. How many stereoisomers of each product could be obained
Homework Equations
See attached image
The Attempt at a Solution
For product 1, there is 1 chiral centre and 1 double bond. ∴No. of products = 22
For 2, it...
Homework Statement
All the substances involved in the reaction given below can undergo combustion reaction and their combustion enthalpies at 300K are given below,
2A(g)+B(g) ----> 3C(g) + D(g)
Given: ΔH A = -1000cal/mol ΔH B= -2000cal/mol ΔH C=-500 cal/mol ΔH D = -100 cal/mol
If the...
Homework Statement
http://i.minus.com/jfUXIXvQJw8hw.png
Homework Equations
Ka of hydrogen sulfate ion will be taken as 1.2x10-2.
Ka of ammonium ion will be taken as 5.6x10-10
Kb of ammonia will be taken as 1.8x10-5
Kb of sulfate ion will be taken as something very tiny (Kw/Ka of...
[b]1. Hi, The problem:
A roof support frame has various leadings on it. The frictionless pin joint at points A has vertical and horizontal reaction forces. The rollers at point B allow free movement in the horizontal direction and has a vertical reaction.
a/Calculate The total Horizontal...
I was not expecting there to be a reaction between aluminum metal and a solution of iron chloride. I thought the aluminum would be oxidized and the iron reduced. What is the reaction that is occurring that is creating hydrogen gas on the surface of the aluminum? I know it has to do with...
http://imgur.com/cIprKmy
To re explain here, I know that (1) is correct as the X is electron rich while the carbon is electron poor so the reaction is correct.
But for (2) I'm not entirely sure if it is correct. if we just consider the electronegativity of X and N Then as drawn N should...
I have seen modern steam turbines with velocity compounding, they start with impulse stage then reaction stages,can anyone tell me, why There is a impulse stage first,why not a reaction stage first?
Homework Statement
The shaft carries two particles of mass m, and rotates about the z-axis with the constant angular velocity ##\omega##. Determine the x- and y-component of the bearing due to imbalance.
The Attempt at a Solution
Rotation only around the ##z-##axis so ##\omega _{x}=\omega...
I am reading a chemistry book printed in 1805. The chemical reaction equations are written using the equality symbol = instead of the arrow →, which is used in modern times.
Anyway sometimes it is still possible to see the "old fashioned" way...
Assume that the arbitrary-shape object shown has a torque applied at the black X with a circle, and is free to rotate about the X axis. Assume that the object is also constrained by a pin at this torque input point, parallel to the X-axis. The CG of the object is the blue plus sign, and there...
Homework Statement
##_{1}^{2}\textrm{D}+_{1}^{3}\textrm{T}\rightarrow _{4}^{2}\textrm{He}+n##
How much energy releases?
Homework Equations
Semi empirical mass formula that we use:
##W=-w_0A+w_1A^{2/3}+w_2\frac{Z(Z-1)}{A^{1/3}}+w_3\frac{(a-2Z)^2}{A}+w_4\frac{\delta...
Hi, this may seem like a noob question for you geeks out there, but I can't wrap my head around this.
The formula for a spontaneous reaction is \DeltaH-T\DeltaS < 0
Basically, since the reaction between hydrogen and oxygen gas has a negative change in enthalpy it must mean that if the...
Homework Statement
The reaction v1A+v2B--->Products is 1st order wrt A and 0 order wrt B.If the reaction is started with [A0] and [B0] find the integral rate equation.
The Attempt at a Solution
I have got ln[A0]/[A0]-v1x=kt but answer is given as ln[A0]/[A0]-v1x=v1kt.Which one is right?
Homework Statement
Lets say you have 1 liter of 2 mol/L methane and the same amount of chlorine. Let's also say that both are liquids since those are most likely to react. Now the only way they can both be liquids is if the temperature is as cold as an antarctic winter so this is not aqueous...
Homework Statement
Rod AB is attached to a collar at A and rests against a roller at C.
a = 107mm,
l = 642mm,
P = 110kN and
Q = 30kN, determine:
The reaction at A (by the vertical rod) (Unit: kN)
The magnitude of the reaction at C (Unit: kN)
Homework Equations
This is my first...
Just a curious question.
How would the rate for a net reaction involving multiple steps of all similar (perhaps exact - i know it's highly unlikely) activation energies be calculated? I've been told to just look at the slowest step (highest EA) in all cases, even if they are similar in...
We were just going over examples of reaction orders in class and I was told 2 things:
1.) Negative reaction orders are possible
2.) An order of 0 says the reaction rate is independent of the reactant concentration(s)
I had a few questions, though.
1.) What exactly constitutes a...
Hello. My teacher and I have had this very intense debate for quite some time now and we need your opinion on this issue. This question is, where does the energy released in a nuclear fission reaction come from? (Please use the terms "nuclear binding energy" and "mass defect")
My take on this...
Suppose in the reaction 2 NO + O2 --------> 2NO2
Why when the the concentration of NO is doubled, the rate increases 4 times, I know that the rate is directly proportional to the square of NO concentration (I don't know why) and it's order of reaction is 2 ( I don't why ). but I still can't...
N2 + 3H2 -----> 2NH3,
For this reaction to occur does one nitrogen have to collide with 3 hydrogen molecules, or should 3 nitrogen molecules collide with 3 hydrogen molecules to break up the bonds? I just brought up this example because of it's stoichiometry not for any other reason. Thanks in...
Homework Statement
I am given the following chemical eqn
TiCl4(g) + O2 → TiO2 (s) + 2Cl2
I am also given some values on the heat of formation and the entropy of the substances but however only at 300Kelvin and i am given some values and the formula to calculate Cp of the substances
The...
Homework Statement
My problem is with a portion of a much larger problem, I'm working on an exercise involving the production of synthesis gas in where there's a reactor in which it is postulated that the following reactions take place:
CH4 + CO2 ⇔ 2CO + 2H2
CO + H2O ⇔ CO2 + H2
CH4 + H2O ⇔ CO...
X + Y + Z -> A + C+ + B-
Initial Concentrations Z= 4.1 X 10^-3M, X=2.3 X 10^-1M, Y= 1.2 X 10^-1 M.
http://s121.photobucket.com/user/marykaywest420/media/81386cf6-e132-4578-8fb5-1024a2a3f3d5_zpscc804723.jpg.html?sort=3&o=0
3. So my attempt included graphing -R/(R∞-R) vs. time. which produced...
Hi
I am tutoring a pupil in high-school out of necessity (no other teachers avail), while I am not so acquainted anymore with chemistry. The pupil showed me a question concerning the calculation of the reaction enthalpy which looked somewhat as follows:
1. Problem statement, all variables...
Homework Statement
To activate the reaction ##(n,\alpha)## with stationary ##B^{11}## nuclei, neutrons must have the activation kinetic energy ##T_{th}=4\,MeV##. ##(n,\alpha)## means that ##n## is bombarded to obtain ##\alpha##. Find the energy of this reaction.
(Ans: ##Q=-11/12 T_{th}##)...
Homework Statement
Investigate
The number of atoms splitting up in a nuclear reaction
and
Bacterial growth
Your investigation should use appropriate formulae and graphs and include information from records of real events. You should aim to show how good the mathematical models are in...
Im going to try my best to write out this chemical equation. Also I'm going to write a forward arrow but it's really it should be the equilibrium arrows.
[Co(H2O)6]2+ + 4Cl- --> [CoCl4]2- + 6H2O
Sorry for that, I don't know how to use the math font or whatever it's called...
Hi, thanks for checking out this thread.
I'm really having a problem with the question because I don't have any foundation.
If you could, would you:
Explain what exactly is going on? Is this an endothermic or exothermic reaction?
What are colligative properties, and what do they have to...
Homework Statement
Rxn: 2SO2 (g) + O2 (g) \Leftrightarrow 2SO3 (g)
If the initial concentration of SO3 is .500 M (moles/liter) @1500K, what are the final concentrations of [SO2], [O2] and [SO3]. Kc = .15
Stop when you get to the cubic equation
Homework Equations
RICE table...
2BH3(g)->B2H6(g)
Which is true?
a)The reaction is always non spontaneous.
b) The reaction is always spontaneous.
c) The reaction is sometimes spontaneous and sometimes not.
d)The reaction is endothermic.
e) two of the statements are right.
I know that deltaSsystem is negative. (Less...
The equation is balanced, but would it actually work?
NaOCH3 + CO2 + H2O → NaHCO3 + CH4O
Or would the reaction simply ignore the water in the left hand side and go,
2NaOCH3 + CO2 → Na2CO3 + H2O + C2H4
Or perhaps a little of both? I'm just starting to teach myself Chemistry, so any insight...
Hello,
I am confused about the following scenario.
Suppose I have the reaction
CO (g) + 2H2 (g) → CH3OH (g)
and I am asked to solve for the heat of reaction at 800 C. My query is the following: when finding the heat of reaction at standard state, which heat of formation I should use...
Okay let's say we have water, sodium hydroxide and hydrogen chloride. What do you think is going to happen? Do you think the pH will be the same, a little higher, or a little lower?
You have this reaction down here:
H2O+NaOH+HCl(assuming they are equal)= H2O+OH-+Na+(positive...
Homework Statement
Determine the enthalpy of this reaction (below).
2NO_{2} \rightarrow N_{2}O_{4}
Homework Equations
Reaction is exothermic if product is more stable than reactants.
Reaction is endothermic if the reverse were true (product less stable than reactants).
The Attempt at a...
Homework Statement
If you are worried about safely driving after a party, I recommend you just not drive! But if you want to
see when you are finally okay to drive, here is a test to see if you are still too “impaired”. Take a dollar bill
and have a friend hold the bill from one of the short...
Homework Statement
Good day! I have a question from my chem HW that is stumping me. Although the answer may be simple, it has eluded me for quite a bit. It regards rate laws and constants of reactions.
Question is as stated: This reaction was monitored as a function of time: AB --> A + B
A...
Homework Statement
Which of the following CAN be made as a pure substance?
Choices are a list of molecular salts.
Homework Equations
According to my teacher the salt cannot be made as a pure substance if the components undergo a large extent acid-base reaction.
The correct choice was...
Hello!
What would be the substance, chemical reaction and technique, to have the highest rate of immediate mass change, back and forth, from low to high and back to low again, as many times as needed - using only homemade DIY, non dangerous materials and equipment?
My intentions are to...
Homework Statement
This is not a homework question, rather, I am just trying to clarify a concept and example in my textbook.
Ammonia is produced by the reaction of Nitrogen (N2) with hydrogen (H2) as shown in this equation.
N2 + 3 H2 --> 2 NH3
The rate of ammonia production is 5.0 x 10-6...
This question relates to rate constants of transition events. The transmission coefficient κ reduces the value of the rate constant compared to the transition state theory (TST) value. I understand κ to be defined as the probability that a reaction coordinate q will proceed to product given that...
I'm wondering what happens in a single displacement reaction if the displacing metal (the one that's going into the solution) reaches it's solubility limit before the other metal in the solution is fully displaced.
Say for example you had a strong silver nitrate solution, and you placed enough...
Homework Statement
Please see attached for problem statement and table of bond energies. My chemistry background is awful and this is from a materials science textbook. The question is, how would I approach/solve 2.31 (only parts b and c).Homework Equations
The Attempt at a Solution
We go from...
1) Is armature reaction seen in all machines ie DC, INDUCTION & SYNCHRONOUS machines ?
(just answer briefly, which all machines exhibit it)
2) Is back emf in DC motor nothing but LENZ'S law, or is the generating action in DC motor called the LENZ's law, or are both same, and I'm confused ...
suppose you have 2 litres of pure hcl in a solution of 4 litres of radioactive h2o , so the concentration of HCl is 1/3 of the whole solution , now suppose you neutralized that solution with Sodium hydroxide , what happens to the radioactive solvent ? is it involved in the reaction ? does its...
Hi,
I need help determining which of the statements are true and false.
http://imgur.com/9BC1Wqf
I know this involves steady state approximation, but I find that when I try it I am never able to rid of all the intermediates.
Please help
Thanks
Homework Statement
Nitrous oxide reacts with ozone to form dinitrogen pentoxide. There are four moles of each reactant and the volume of the container in which this reaction takes place is 2 L. T is constant. The equilibrium constant for this reaction is 1. How many moles of product are...
Can anyone please walk me through the mechanism as this question does not make sense to me. I do have some understanding of the general mechanism. The answer is B) but I don't understand how to get there.
The confusing aspect to me, is the structure of the ylide.
Homework Statement
Reaction: 2A --> C
Step 1: A <-> M (fast)
Step 2: M + A -> C (slow)
What is the observed rate law?
Homework Equations
Rate = k[A][B][...]
The Attempt at a Solution
The observed rate law seems to be k[A]^2.
However, why is it so? Why does the rate...